1. Field of the Invention
The present invention relates to a verification apparatus, verification method and verification program, and is preferably applied to biometric verification, for example.
2. Description of the Related Art
Biometric verification is often used to prevent identity theft. There is an authentication apparatus (or a verification apparatus) that generates physical trait information from a person's physical trait (such as blood vessel pattern, voice pattern, lip's pattern or the like), which is difficult for someone to forge, and then uses it to identify a user.
Typically, the authentication apparatus has a database that stores the physical trait data of a plurality of legitimate users as “registrant identification data” (a user who has been already registered in the apparatus is also referred to as a “registrant”). To verify a user (a user to be verified is also referred to as a “verification-target user), the authentication apparatus generates from him/her verification-target user's blood vessel image data and then compares it with a plurality of blood vessel image data registered in a database. The authentication apparatus continues it until it finds a matched image.
Theoretically, the authentication apparatus has to check at least half of the registered blood vessel image data until it finds a matched one. Accordingly, it may take a long time to find a matched one if there are a lot of users registered in the database.
As disclosed in Jpn. Pat. Laid-open Publication No. 2006-18676), there is a system that ranks each user's registered blood vessel image data in a certain manner: the registered blood vessel image data of users who have been authenticated frequently are ranked at high. The system checks up the database in that order (also referred to as a “checkup order”). This increases efficiency.